It either the developer poorly constructed the area / not properly compacted the soil or there is a soil movement underground water causes the cavity.

Your house new or old ? Still can ask the developer to rectify if within can’t remember think within 6 years or so … falls under latent defect …structure defect you can’t see after DLP period ended…

If not can try ask your majlis /council and make a report if you think that area is within the council jurisdiction.

Hope this help
Cheers mate
izwan
Www.archidstudio.com